1. Field of the Invention
The present invention relates to a power system, apparatus and method for utilizing waste heat from high temperature application such as kilns, furnaces, incinerates, or other facilities that generate gas streams with utilizable thermal energy capable of conversion to electric energy. The process and system is designed to convert thermal energy (heat) into mechanical work and then to electrical power.
More particularly, the present invention relates to a power system, apparatus and method for utilizing waste heat from high temperature application such as kilns, furnaces, incinerates, or other facilities that generate gas streams with utilizable thermal energy capable of conversion to electric energy, where the system includes a two stage turbine subsystem, a distillation-condensation subsystem and a boiler subsystem in a multiple pressure thermodynamic cycle using a multi-component working fluid comprising at least one lower boiling component and at least one higher boiling components such as an ammonia-water working fluid.
2. Description of the Related Art
In the prior art there exists a system that uses as working fluid a mixture of at least two components, (preferably, an ammonia-water mixture). This system has demonstrated superior efficiency over the conventional Rankine cycle systems. Now referred to a the Kalina Cycle.
These systems comprise two major subsystem: the boiler-turbine subsystem and the distillation—condensation subsystem. However, these systems had some significant shortcomings. The distillation-condensation subsystem used only the higher temperature portion of the available heat from the turbine exhaust. The simplest distillation-condensation subsystem in the prior art required eight separate heat exchangers (see, e.g., U.S. Pat. No. 4,489,563) and did not utilize the lower temperature portion of the heat from the turbine exhaust.
More complex distillation-condensation systems did utilize this lower temperature portion of the heat of the turbine exhaust, but required several additional heat exchangers (see, e.g., U.S. Pat. No. 5,095,708).
In boilers of the prior art systems, a significant reduction of thermodynamical loses was achieved when it was possible to attain a perfect balance between the available heat and heat load in the low temperature portion of the boiler, (i.e., in the process of pre-heating the working fluid up to a boiling point temperature). ‘This in its turn required that the initial temperature of the heat source be relatively high. In such cases where the initial temperature of a heat source is lower, then balancing of the available heat with the heat load in the high temperature portion of the boiler (i.e., the portion of the boiler where the vaporization and superheating of the working fluid occurs) leaves significant excess heat in the low temperature portion of the boiler, (i.e., the pre-heater). This excess heat is not only utilized, and this has an adverse effect on the overall efficiency of the system.
Moreover, in some cases, the gas which “carries” the heat to be utilized contains corrosive components. An example of this occurs with flue gas in cement kilns. In such a case, the gas cannot be cooled below a specific temperature, since if the gas is cooled to far, there would be a condensation of corrosive components of the gas on the surface of the heat exchanger, which would result in acute corrosion. Thus, the stream of working fluid must be pre-heated, since if the stream were to be too cool, and the pipes of the heat exchangers in which this working fluid is held were to be exposed to corrosive flue gas, then the result would be the condensation of some components of the flue gas on some of the components of the heat exchanger. In such a case, even in the bulk of the flue gas were to be at sufficiently high temperature, there would still be precipitation of corrosive materials onto the heat exchanger.
Thus, there is a need in the art for a new power system, apparatus and method designed to eliminate or ameliorate the shortcomings that exist in the prior art.